While some may say that flour can be stored for up to a full year at room temperature, unless you know how the flour was stored prior to your purchase (fat chance of that) you would be best advised to re-bag the flour into double plastic bags (like bread bags) and then store anything that you will not be using within the next month or so under refrigeration or in the freezer. Your main concern is insect infestation. You may not always see the black or reddish appearance of flour beetles (looks like pepper in the flour) as you can also have the larval stage present. This is when the flour is said to be "wormy". About the only way you'll be aware of this is if you sift the flour, then you will see the larva in the screen after sifting the flour. An old baker's trick is to freeze the flour for 45-days, this will kill all of the insect stages (from adult to eggs), then transfer the flour to a cooler where it can be stored for a much longer period of time if necessary. For the most part, flour is pretty free from insects as it comes from the mill, it is the post packaging contamination that gets it. The problem can/will occur in a warehouse, truck, or other transport, and all too often on a store shelf. And don't over look your own kitchen, I've had to discard buggy flour more than once from my own kitchen, especially when you store the flour in a drawer as I used to do. I now store it in a large glass jar.
Tom Lehmann/The Dough Doctor